Profile dressing mechanism for grinding wheels



Jam 27, 1970 w. P. FLoHR, JR I 3,49

PROFILE DRESSING MECHANISM FOR GRINDING WHEELS Filed Dec. 26, 1967 3 Sheets-Sheet l INVENTOR LmLUAM P. FLOHR,dr.

ATTORNEYS Jan 27, 1970 w. P. FLOHR, JR I 3, 9

PROFILE DRESSING MECHANISM FOR. GRINDING WHEELS Filed Dec. 26, 1.967 I 5 Sheets-Sheet 2 5 2 g a, .q xi qwt 0 "m 1, I $8 0 E m l I I 5 m *1 m w m H i d- W Z INVENTOR g umum P. FLOHR,Jn

ATTORNEY 5 United States Patent 3,491,741 PROFILE DRESSING MECHANISM FOR GRINDING. WHEELS William P. Flohr, Jr., Waynesboro, Pa., assignor to Litton Industries, Inc., a corporation of Delaware Filed Dec. 26, 1967, Ser. No. 693,550 Int. Cl. B28d 1/16 US. Cl. 125-11 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a mechanism for dressing a peripheral grinding face of a grinding wheel or wheels and consists of a motor driven diamond impregnated roller mounted on a dresser bar which is movable along a path corresponding to the profile of the grinding wheel. At the beginning of a dressing operation, the'roller is rotated as it first passe-s across the peripheral face of the grinding wheel. Thereafter, the direction of movement is reversed and the roller is held stationary as it passes across the peripheral face of the grind-ing wheel in the opposite direction. Where the grinding Wheel has rounded corners, the rollers is rotated as it passes first across the peripheral face and one of the corners of the grinding wheel. Thereafter, the direction of movement is reversed and the roller is held stationary as it passe-s across the peripheral face of the grinding wheel in the opposite direction. Where the grinding wheel has rounded corners, the roller is rotated as it first passes across the peripheral face and one of the corners of the grinding wheel. Thereafter, the direction of movement is reversed and the roller is held stationary as it passes across the peripheral face of the grinding wheel in the opposite direction until the point of merger of the other corner and the peripheral face is reached, at which time, rotation is again imparted to the dressing roller as it passes around said corners.

This invention relates to a grinding wheel dressing mechanism of the type disclosed in commonly assigned US. Patent No. 3,121,423 in the name of R. E. Price et al. granted Feb. 18, 1964. Dressing mechanisms of the type disclosed in the above-noted patent employ a con tinuously rotating diamond impregnated roller which moves along a path determined by one or more profile bars and a follower. The path followed by the dressing roller corresponds generally to the profile of the grinding wheel face and corners, and during a typical dressing operation the dressing roller is first moved across the cylindrical grinding face and one of the corners. Upon the return pass the dressing roller again passes across the cylindrical face and then around the opposite corner to complete the dressing operation. However, during both the initial and the return pass the dressing roller is continuously rotated and therefore, a relativley heavy or coarse cut is taken during the dressing operation. This is highly undesirable because particularly the cylindrical grinding face of the grinding wheel is not dressed to the degree necessary to maintain the close tolerances required for such components as the crankpins of automotive crank-shafts. In order to maintain such close tolerances it is, therefore, imperative to dress grinding wheels as perfectly as is commercially practical.

In accordance with this invention it has been found that by maintaining the diamond dressing roller stationary during the return pass thereof across the cylindrical face of the grinding wheel one or at most a few of the impregnated diamonds contact the cylindrical face, as opposed to the conventional practice of rotating the dressing roller during the return pass at which time many more of the diamonds engage the cylindrical face resulting "ice in the coarse dressing cut heretofore noted. However, by holding the dressing roller stationary only one or a few of the diamonds contact the cylindrical face of the grinding wheel and a very light finishing dress-ing cut is produced.

It is, therefore, a primary object of this invention to provide a novel dressing mechanism which includes means for terminating the rotation of a dressing roller prior to the return pass thereof across the cylindrical face of a grinding wheel to produce a light dressing cut which correspondingly effects an accurate dressing of the grinding wheel.

A further object of this invention is to provide a novel dressing mechanism of the type aforesaid wherein the dressing roller is maintained in a non-rotatable condition only upon the return pass thereof across the cylindrical grinding face of the grinding wheel, and control means are provided for rendering the dressing roller rotatable during the movement of the dressing roller around each of the grinding wheel corners.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the drawings:

FIGURE 1 is a side elevational view partly in section of a grinding wheel dressing mechanism, and illustrates a diamond impregnated dressing roller carried by the grinding machine dresser bar.

FIGURE 2 is an enlarged fragmentary sectional view taken generally along line 2-2 of FIGURE 1, and illustrates a brake mechanism for preventing rotation of the dressing roller, and means for actuating the brake mechanism for stopping the rotation of the dressing roller.

FIGURE 3 is a highly schematic top plan view of a profile bar and follower, and illustrates the manner in which the profile bar and follower cooperate for imparting movmeent to the dressing roller along a predetermined path relative to the grinding wheel during a dressing operation.

FIGURE 4 is a diagrammatic top view of the grinding wheel dressing mechanism of this invention, and illustnates hydraulic control means and associated switches for controlling the movement of the dressing roller during a dressing operation.

FIGURE 5 is an illustration of the control circuit for the grinding wheel dressing mechanism.

A dressing mechanism constructed in accordance with this invention is best illustrated in FIGURES 1 and 4 of the drawings, and is generally designated by the reference numeral 10. The dressing mechanism 10 includes a dresser bar 11 to which is secured a bracket 12 (FIGURE 1) which in turn carries a housing 13. A motor 14 is secured atop the housing 13 and includes a coupling 15 connecting a drive shaft 16 of the motor 14 to a shaft 17 carrying a diamond impregnated dressing roller 18. The coupling 16 includes a peripheral flange 20 which is in alignment with a plunger 21 of a braking or locking mechanism 22 (FIG- URE 2). The locking mechanism 22 includes a housing 23 secured to the housing 13, and has a fluid chamber 24 into which is introduced a control fluid, such as pressurized air, for shifting the plunger 21 to the left against the force of a spring 25. A solenoid valve SOL 30 (FIGURE 4) is connected to a valve 29 in a conduit 26 opening into the chamber 24. Upon the starting of the motor 14 the solenoid valve SOL 30 is operated to vent the line 26 to the atmosphere whereupon the spring 25 moves the plunger 21 to the non-braking or unlocked position shown in FIG- URE 2. However, when the motor 14 is stopped the solenoid SOL 30 is shifted to direct fluid under pressure into the chamber 24 to shift the piston 21 to the left as viewed 3 in FIGURE 2 causing the contact of the end thereof with the flange 20 to thus prevent rotation of the dressing roller 18 in a manner and for a purpose which will be more fully described hereinafter.

The bracket 12 of the dresser bar 11 supports the dressing roller 18 at a slight angle to the vertical in the direction of a grinding wheel 27 so that, as the dresser bar 11 advances the roller 18 towards the grinding wheel 27, the initial contact of the roller 18 with a face F of the grinding wheel 27 will be at its upper peripheral edge leavinga small space between the remainder of the dressing roller face and the grinding wheel face. Coolant from a nozzle 28 is directed into this space, as indicated by the unnumbered headed arrow in FIGURE 1, to maintain the dressing roller 18 and the grinding wheel 27 relatively cool during a dressing operation. The flow of the coolant into the space is also augmented by the pumping action developed by the grinding wheel 27 as the peripheral or cylindrical surface F thereof moves upwardly at this point.

The manner in which the transverse and longitudinal movement is imparted to the dressing roller 18 by the dressing mechanism 10 is similar to that disclosed in the aforementioned patent and includes a carriage member 30 mounted on a portion of the grinding wheel support (not shown) for sliding movement in a plane parallel to the axis of the grinding Wheel 27. A piston rod 31 is connected at one end of the carriage member 30 and an opposite end thereof carries a piston 32 which is reciprocally mounted in a cylinder 33. Fluid from a conventional pump 34 is introduced to the left of the piston 32 as viewed in FIGURE 4 by a conduit 35, a conduit 36, a conventional spool valve 37 and a conduit 38 to impart left-to-right movement to the piston 32 and the carrier member 30 upon the actuation of a solenoid SOL 33 in a manner which will be more apparent hereinafter. Movement of the carriage member 30 from right-to-left in this same figure is effected by introducing fluid into the cylinder 33 to the right of the piston 32 over a path defined by the conduit 35, the conduit 36, the valve 37 and a conduit 41 upon the actuation of a solenoid valve SOL 34.

The movement of the dressing bar 11 toward and away from the grinding wheel 27 consists of a cylinder 46 attached to a dresser slide 45 and having a piston 47 on a rod 48 attached by means of a bracket (not shown) to the carriage member 30. Fluid introduced into the cylinder 46 continually urges the dresser slide 45, the dresser bar 11 and the dressing roller 18 carried thereby toward the grinding wheel 27, and functions to maintain contact between a follower 50 and a profile bar 51 (FIGURES 3 and 4) in a manner more fully described in the latternc-ted patent. Fluid is also introduced into the cylinder 46 to move the dressing roller 18 away from the grinding wheel 27.

A limit switch 29LS controls the transverse movement of the carriage member 30 while the in-and-out movement of the dresser slide 45 is controlled by switch 30LS. The switch 29LS is actuated by abutment 56 carried by the bracket 58 which is, in turn, secured to the carriage member 30. The switch 30LS is likewise actuated by abutment member 60 carried by the dresser slide 45.

A dressing operation of the drawing mechanisms 10 will now be described in conjunction with the circuit of FIGURE 5, it being assumed that the dressing roller 18 is stationary and is situated at position A in FIGURE 3 at which a plane P of the cylindrical grinding wheel face F is generally tangential to the face of the dressing roller 18. In this position of the dressing roller 18 the follower 50 is, of course, correspondingly positioned relative to the profile bar 51, as is also shown in FIGURE 3.

The dressing operation is initiated when a counter (not shown) counts out and closes the contact CTR2 (FIG- URE 5) to complete a circuit through normally closed contact 94CR1 which energizes the relay 88CR. A contact 88CR1 of the relay 88CR is a holding contact in the circuit with normally closed reiay contact 86CR1. The energized relay 88CR also closes a contact 88CR2 in a circuit to energize a relay 94CR which in turn establishes a hoiding circuit through a contact 94CRi, a normally closed contact 84CR1, and a parallel normally closed contact 86CR2. With the closing of contact 94CR2 a circuit is completed through the previously closed contact 88CR3 to energize a relay 118CR and a timer relay 18TR. The contact 94CR2 also completes a circuit through a normally closed contact CR1 and now closed contact 88CR4 to energize a relay 990R closing contact 99CR1 and energizing the solenoid SOL 33 (FIGURES 4 and 5).

The solenoid SOL 33 shifts the valve 37 in a manner to direct fluid from the pump 34 and through the conduits 35, 36 and 38 to the left side of the piston 32 to shift the piston 32, the rod 31, the carriage member 30 and the dressing roller 18 to the right, as viewed in FIGURE 4 which is downwardly as viewed in FIGURE 3. At the same time the contact 94CR2 completes a circuit with the closed contact ,88CR3 to energize the timer relay 18TR which closes contact 18TR1 after a predetermined interval to energize the dresser motor 14, allowing enough time for the solenoid SOL 30 to release the braking plunger 21 upon the closing of the contact 118CR2 before the motor 14 is started. The solenoid SOL 30 shifts the valve 29 to its exhaust position thereby venting the conduit 26 to the atmosphere whereupon the spring 25 (FIGURE 2) shifts the plunger 21 to the right as viewed in this latter figure to unlock or release the dressing roller 18 whereupon the same is rotated by the energized motor 14.

As the dressing roller 18 rotates and moves from position A downwardly as viewed in FIGURE. 3 it engages the cylindrical face F of the grinding wheel 27 at a point B in advance of merger between a corner or radius R1 and the face F of the grinding wheel 27. The motor 14 remains energized during the movement of the dressing roller 18 across the face F of the grinding wheel 27 and around the other corner or radius R2 until the radial inward movement of the dressing slide 45 closes the limit switch 30LS by means of the abutment 60 to energize the relay 86CR.

The contact 86CR1 opens to de-energize the relay 88CR which opens the contact 88CR3 to de-energize the relay 18TR and the motor 14, thereby stopping the rotation of the dressing roller 18 while at point C. The deenergized relay 118CR also opens the contact 1180122 to de-energize the solenoid SOL 30 whereupon the fluid from the pump 34 is introduced behind the plunger 21 through the valve 29 and the conduit 26 to shift the plunger 21 to the left as viewed in FIGURE 2 to its unlocked position. At this point the dressing roller 18 is at point C. The dressing roller 18 is then shifted to point G in the manner described in the aforementioned patent at which position the face of the dressing roller 18 is again generally tangentially related to radius R2 and the face F of the grinding Wheel 27 along the plane P.

At this time the contact 88CR4 opens to de-energize the solenoid SOL 33 permitting the valve 37 to return to its central position. However, at the same time the normally closed contact 88CR5 closes to complete a circuit through normally closed contact 99CR1 to energize relay 100CR and the solenoid SOL 34.

The fluid from the pump 34 is therefore introduced into the cylinder 33 through the conduit 36, the valve 37 and the conduit 41 causing the piston 32, the rod 31, the carriage member 30 and the dressing roller 18 to move from point G across the face F of the grinding wheel 27 toward point B, during which time the dressing roller 18 remains stationary to take a light finishing dressing cut across the cylindrical face F of the grinding wheel.

As the dressing roller 18 moves with the carriage member 30 to the left as viewed in FIGURE 4 the limit switch 29LS is closed by the abutment member 56 completing a circuit to energize relay 84CR to start rotation of the dressing motor 14 at the time the dressing roller 18 reaches the merging point B between the radius R1 and the face F, and during the remainder of the time the dressing roller 18 moves along this radius under the guidance of the profile bar 51 and the cam follower 50. The radius R1 is therefore dressed while the dressing roller is rotating, and the rotation continues until the dressing roller 18 reaches point H at which time the limit switch 30LS is actuated, energizing the relay 86CR. The normally closed contact 86CR1 opens to de-energize relay 88CR Which opens contact 88CR2 to de-energize the relay 94CR. The de-energized relay 94CR causes the contact 94CR2 to open thereby stopping the dressing motor 14, applying the locking plunger 21 against the flange 20, and also discontinues the traverse movement at point A by the de-energizing of the solenoids SOL 33, SOL 34. The dressing roller 18 is thereby again positioned as shown in FIGURE 3, and further dressing operations by the dressing mechanism can again be performed in the manner just described.

While preferred forms and arrangement of parts have been shown in illustrating the invention, particularly grinding wheels having rounded corners, it is to be clearly understood that various changes in details and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claimed subject matter. For example, in many cases, the use of a brake to prevent rotation of motor 14 is unnecessary, the friction and inertia in the motor and roller mounting being sufiicient to prevent rotation of said roller after the current to the driving motor 14 is cut off.

I claim:

1. A mechanism for dressing a grinding wheel having a peripheral grinding face merging with rounded corners comprising a dressing roller, means for moving said dressing roller along a path corresponding to th profile of the grinding face and corners, means for rotating the dressing roller during the movement thereof across at least one of the corners and the grinding face to thereby perform a relatively heavy cutting operation, and means for maintaining the dressing roller non-rotatable during another movement thereof across the grinding face to thereby perform a relatively light cutting operation.

2. The mechanism as defined in claim 1 wherein the movement of the rotating dressing roller across the grinding face is in a direction opposite to the movement of the non-rotating dressing roller across the grinding face.

3. The mechanism as defined in claim 1 wherein said rotating means is further operative for rotating the dressing roller during the movement thereof across the other of said corners.

4. The mechanism as defined in claim 1 wherein the movement of the rotating dressing roller across the grinding face is in a direction opposite to the movement of the non-rotating dressing roller across the grinding face, and said rotating means is further operative for rotating the dressing roller during the movement thereof across the other of said corners.

5. The mechanism as defined in claim 1 including first control means for activating said rotating means prior to the first-mentioned movement of the dressing roller, and second control means for activating said maintain ing means prior to the second-mentioned movement of the dressing roller across the grinding face.

6. The mechanism as defined in claim 1 wherein said rotating means includes a rotatable shaft carrying said dressing roller, and said maintaining means is a brake mechanism for holding said shaft non-rotatable during said second-mentioned movement.

7. The mechanism as defined in claim 3 wherein the path followed by the dressing roller during the firstmentioned movement is in a first direction beginning adjacent said other corner and proceeding across the grinding face and then around said one corner, and during the second-mentioned movement is in an opposite direction beginning adjacent said one corner and proceeding across the grinding face and then around said other corner.

8. The mechanism as defined in claim 3 wherein said rotating means includes a rotatable shaft carrying said dressing roller, and said maintaining means is a brake mechanism for holding said shaft non-rotatable during said second-mentioned movement.

9. The mechanism as defined in claim 7 wherein said rotating means includes a rotatable shaft carrying said dressing roller, and said maintaining means is a brake mechanism for holding said shaft non-rotatable during the movement of the dressing roller in the opposite direction across the grinding face.

10. The mechanism as defined in claim 9 including control means for activating said brake mechanism to render said shaft non-rotatable after said dressing roller has moved around said one corner, and control means for deactivating said brake mechanism to render said shaft rotatable as said dressing roller begins its movement around said other corner.

11. A mechanism for dressing a grinding wheel comprising a dressing roller, a motor for rotating said roller, means for traversing said roller alternately in opposite directions across said grinding wheel during a dressing operation, means for effecting the rotation of said roller during traversing movement in one direction, and means for preventing the rotation of said roller during traversing movement thereof across the grinding wheel in the op posite direction.

12. The mechanism as defined in claimll wherein said dressing roller is mounted for rotation in a plane normal to the plane of the grinding wheel and inclined to the grinding face thereof so that initial contact with the grinding wheel is on one edge of said roller.

13. The mechanis mas defined in claim 11 wherein the grinding wheel has rounded corners, and means are provided for guiding said roller around said corners.

14. The mechanism as defined in claim 13 wherein control means are provided for maintaining said rollers rotating as the roller is guided around said corners.

15. The mechanism as defined in claim 1 wherein said dressing roller is mounted for rotation in a plane generally normal to the plane of the grinding wheel, and means are provided for supporting the dressing roller with its axis inclined to the face of said grinding wheel whereby the initial contact between the grinding wheel face and the dressing roller is at an edge of the dressing roller.

References Cited UNITED STATES PATENTS 3,273,555 9/1966 Seidel -11 2,528,621 11/1950 Sweetser 12511 X 3,121,423 2/1964 Price 12511 3,067,732 12/1962 Balsiger 125-11 3,313,285 4/1967 Price 12511 HAROLD D. WHITEHEAD, Primary Examiner 

